/*
 * Copyright (C) 2011-2014 GUIGUI Simon, fyhertz@gmail.com
 *
 * This file is part of libstreaming (https://github.com/fyhertz/libstreaming)
 *
 * Spydroid is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this source code; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package net.majorkernelpanic.screening.rtp;

import android.util.Log;

import java.io.IOException;

/**
 *   RFC 4629.
 *
 *   H.263 Streaming over RTP.
 *
 *   Must be fed with an InputStream containing H.263 frames.
 *   The stream must start with mpeg4 or 3gpp header, it will be skipped.
 *
 */
public class H263Packetizer extends AbstractPacketizer implements Runnable {
  public final static String TAG = "H263Packetizer";

  private Statistics stats = new Statistics();
  private Thread t;

  public H263Packetizer() {
    super();
    socket.setClockFrequency(90000);
  }

  public void start() {
    if (t==null) {
      t = new Thread(this);
      t.start();
    }
  }

  public void stop() {
    if (t != null) {
      try {
        is.close();
      } catch (IOException ignore) {}
      t.interrupt();
      try {
        t.join();
      } catch (InterruptedException e) {}
      t = null;
    }
  }

  public void run() {
    long time, duration = 0;
    int i = 0, j = 0, tr;
    boolean firstFragment = true;
    byte[] nextBuffer;
    stats.reset();

    try {
      while (!Thread.interrupted()) {

        if (j==0) buffer = socket.requestBuffer();
        socket.updateTimestamp(ts);

        // Each packet we send has a two byte long header (See section 5.1 of RFC 4629)
        buffer[rtphl] = 0;
        buffer[rtphl+1] = 0;

        time = System.nanoTime();
        if (fill(rtphl+j+2,MAXPACKETSIZE-rtphl-j-2)<0) return;
        duration += System.nanoTime() - time;
        j = 0;
        // Each h263 frame starts with: 0000 0000 0000 0000 1000 00??
        // Here we search where the next frame begins in the bit stream
        for (i=rtphl+2;i<MAXPACKETSIZE-1;i++) {
          if (buffer[i]==0 && buffer[i+1]==0 && (buffer[i+2]&0xFC)==0x80) {
            j=i;
            break;
          }
        }
        // Parse temporal reference
        tr = (buffer[i+2]&0x03)<<6 | (buffer[i+3]&0xFF)>>2;
        //Log.d(TAG,"j: "+j+" buffer: "+printBuffer(rtphl, rtphl+5)+" tr: "+tr);
        if (firstFragment) {
          // This is the first fragment of the frame -> header is set to 0x0400
          buffer[rtphl] = 4;
          firstFragment = false;
        } else {
          buffer[rtphl] = 0;
        }
        if (j>0) {
          // We have found the end of the frame
          stats.push(duration);
          ts+= stats.average(); duration = 0;
          //Log.d(TAG,"End of frame ! duration: "+stats.average());
          // The last fragment of a frame has to be marked
          socket.markNextPacket();
          send(j);
          nextBuffer = socket.requestBuffer();
          System.arraycopy(buffer,j+2,nextBuffer,rtphl+2,MAXPACKETSIZE-j-2);
          buffer = nextBuffer;
          j = MAXPACKETSIZE-j-2;
          firstFragment = true;
        } else {
          // We have not found the beginning of another frame
          // The whole packet is a fragment of a frame
          send(MAXPACKETSIZE);
        }
      }
    } catch (IOException e) {
    } catch (InterruptedException e) {}

    Log.d(TAG,"H263 Packetizer stopped !");
  }

  private int fill(int offset,int length) throws IOException {
    int sum = 0, len;

    while (sum<length) {
      len = is.read(buffer, offset+sum, length-sum);
      if (len<0) {
        throw new IOException("End of stream");
      }
      else sum+=len;
    }

    return sum;
  }
}
